DECEMBER 1963 



MARCH 1964 



DIRECTION OF FLOW 



PERCENTAGE OF TOTAL 

 5 10 15 20 



WEEKS 



25 



— I — 



FiQTJEE 14. — Movement of holdover fall Chinook salmon from Brownie© Reservoir in relation to water temper- 

 ature. (The early outmigration coincided with the approach of a mass of cold water.) 



cated that these fish were wandering. As the season 

 progressed, however, the increases in the propor- 

 tion and rate of movement downreservoir suggest 

 the onset of a directed migration (fig. 15). 



The holdover of fingerling salmon in Brownlee 

 Reservoir was evident during each year of study, 

 but the percentage of the total involved, as indi- 

 cated from reservoir recruitment and escapement 

 estimates (Krcma and Raleigh, 1970; Sims, 1970), 

 fluctuated significantly. The percentage of hold- 

 overs seemed to be smallest in 1965, intermediate 

 in 1964, and highest in 1963. The yearly percent- 

 age of holdovers varied inversely with reservoir 

 conditions conducive to good passage of fish (figs. 

 4 and 5). 



KOKANEE OF AGE-GROUP I 



A few kokanee were caught in the reservoir in 

 1963 and 1964, and large numbers entered the 



reservoir in 1965 (table 3) . The fish were probably 

 from the Payette River system (Payett« Lakes and 

 Cascade and Deadwood Reservoirs). The migra- 

 tion appeared each year in early June, peaked in 

 mid- to late June, and continued into July. Too 

 few fish were present in 1963 or 1964 to determine 

 movement within the reservoir. In 1965, however, 

 it was evident from gill net catches and the 

 recapture of tagged fish that through June the mi- 

 grants consistently moved downreservoir. By mid- 

 July, when the reservoir was full and the outflow 

 was greatly diminished, fish were moving upres- 

 ervoir and downreservoir in about equal numbers. 

 Kokanee were captured near the surface early 

 in the migration, but as the season progressed and 

 the environment deteriorated, the population 

 was concentrated near the dam at depths of 18 to 

 47 m., as were other salmon species that held over 

 (fig. 13). 



236 



U.S. FISH AND WILDLIFE SERVICE 



